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If the spigot you tested your flow from was supplied from a 1/2" line, which is not uncommon, then a flow of 8 GPM would be correct given your psi. You need to understand that when testing flow, there are tons of variables. Every elbow the water flows through, different shut off valves, and hose bibs, all restrict flow. If I were to test your flow and found 8 GPM coming from a 1/2" supplied hose bib, I would more than likely design for 12-15 GPM given that your pressure is more than adequate. The down side is that, if in fact your supply line is indeed 3/4", the velocities will be on the high end of the scale throughout your supply line.

I would say, a rotor zone consisting of 4 heads would be fine, even on a 3/4" supply line.

A 1" supply line is what most irrigation companies like to see. It allows us to flow that 12-15 GPM without worrying about water hammer and destructive velocities. However, lots of systems get plumbed into 3/4" and do just fine in that 12 GPM flow range.

I'm sure there's gonna be some guys that are gonna hate me for saying this, but why not contact a few reputable Irrigation companies in your area and schedule a few "free estimates". Mention your concerned about your water supply and ask if they'll test it for you. Ask the right questions and you may just get your answer.

Im not 100% sure its galvanized, it was dusk, and it was covered with dirt. Could it be steel? I'll check tomorrow. But how would one know its restricted, except to cut it out and replace it? And what size/type of supply line would you replace it with...on a 5/8" water meter? I am pretty sure about the pressure readings, but I'll try it at different times, and on different days. As far as the line I took the pressure readings from, they are just typical outside faucets? Not sure what size, guess I can check that tomorrow...but if they are 1/2", how would that affect the overall issue? Sorry for so many questions, Im a newb at this, learning as I go. Im looking at the diagram of my system, and the "mainline" that runs through the yard is 1 1/4", which then branches out to 3/4, and finally down to 1/2" pvc....

Im amazed that a 3/4" supply line coming from the main can supply all of these lines....although...its not doing that great of a job....so...yeah....

I guess im just surpised its standard, when everything I seem to read online says that a 1" supply line is the current minimum, and all of the "do it yourself" sprinkler system design websites show systems running at like 15 GPM, and if you have less than 7 GPM, they dont offer their service, and say to "call them for other options"...

A 5/8" meter attached to a 3/4" supply line is pretty standard. The meter is generally always sized down from the size of the supply line. Upsizing water meters isn't gonna gain a whole lot. My concerns are the fact that you have a 3/4" galvanized supply line. Depending on the age of the pipe, it could be severely restricting your flow from being rusted/corroded on the inside. I have cut out numerous feet of galvanized piping for this fact alone.

If you're confident your pressure readings are correct, which doesn't sound like it, check the size of pipe that you took your flow reading from. It may be 1/2" for all I know. Or stay on the safe side and design for 9-10 GPM (3/4" supply line).

I would contact a plumber and see what he has to say about the supply line, flow, and psi. They're usually cheaper than getting the city out to look.

A 1" service line is more than enough to handle your needs, especially if your static pressure is in the 80-90 range.

Whats the chance of getting the water co. to install a larger meter? And what the hell do I do about the supply line to the house? Anything after the meter is my responsibility, right? Can I just call out a plumber and have them do it? I have no clue.

And if so...how big is "too big"...ie...what would y'all suggest to prevent too much scrubbing and water hammer etc...(although, I probably shouldnt worry about that at this point)

But, theres some kind of metal collar around the outside of the faucets outside the house. Stuck my finger in there, and theres a rubber nipple extending down from the faucet??? and the water is pretty aerated...so I dont know what the hell that is, and if thats restricting the flow, and giving me the horrible GPM estimate that Im getting which is like 8.5 GPM.

ok..so its a hose bib vacuum breaker....does that reduce flow rate??

I should probably mention, I live in Texas, and were in a HISTORICAL drought...but my pressure is good, so i dont get why Im only getting 8.5 GPM. Wonder if Im going to have enlarge the supply line to the house?

PSI/Flow Rate

hey guys,

Im trying to rehab an old system I inherited....and Im replacing a bunch of valves, and fixing a bunch of leaks. I wanted to gauge my PSI and flow rate, just to know what to expect in terms of performance when I fix everything back to where its supposed to be. My wife picked up a water pressure gauge for me at home depot, but damnit, its a cheapass orbit meter. The first time I hook it up, it fills with water...sigh....and I got readings varying from 80 to 96, all within 30 min, but the average was about 90 psi. So...dont know what to estimate for psi.

I went to the water meter, and haha...cant get it open, and the size of the meter isn't stamped on the box. Should I dynamite it open, or just estimate that its 5/8"? So.....also cant tell what size pipe is supplying the house, cuz I cant get in the meter. Theres no pipe visibly going into the house....the first pipe visible is coming out of the wall to the water softener in the garage, and its about 2 3/4-or 3 inches around...so this is a 3/4" copper line???

The Topper is when I tried to test he GPM. It took 35 seconds to fill a 5 gal. bucket. But, theres some kind of metal collar around the outside of the faucets outside the house. Stuck my finger in there, and theres a rubber nipple extending down from the faucet??? and the water is pretty aerated...so I dont know what the hell that is, and if thats restricting the flow, and giving me the horrible GPM estimate that Im getting which is like 8.5 GPM.

Frack...I couldnt have failed more miserably at this if I tried. Im going to start drinking heavily again.